The invention relates to a head lamp for dimming light or fog light of motor vehicles. A head lamp is known from DE-OS No. 33 34 450, for example, whose lens must have a relatively large opening, so that the light beam illuminates the roadway sufficiently, and also sufficiently illuminate the edges thereof. The dispersion of the light beam, i.e., the splitting up of color of the light beam, in particular by the lens causes a color edge at the light-dark border of the light beam. This color edge, which is generated by color location errors, i.e. chromatic aberration, is annoying; moreover, such a light beam does not comply with legal requirements.
In order to eliminate this disadvantage, at least two lenses are used, of which at least one lens has a negative power of refraction. Such a multiple part lens requires considerable technical manufacturing efforst which is not acceptable for head lamps of motor vehicles.